The embodiments described herein relate to design and construction of electromagnetic solenoids, and more particularly, to a solenoid assembly designed and configured to have a controlled reluctance based on air gap geometries, leading to a controlled magnetic force during the operation of the solenoid assembly.
Known solenoid assemblies are used in a variety of different applications. For example, known solenoid pumps are used in a variety of vehicle applications, such as, for example, to transfer oil, fuel and/or other fluids to facilitate the operation of the vehicle.
Solenoid pumps can be configured to receive an electrical current to cause an armature to move, thus actuating a pumping mechanism to enable transfer of fluid. In most known systems, the armature can be moved along a fixed stroke length, wherein the distance between two end-stops is fixed. Similarly stated, in normal operation, when the solenoid is actuated, the armature moves a fixed distance or “stroke.” An actuator rod can be coupled to the armature such that movement of the armature results in a corresponding movement of the actuator rod, which actuates the pumping mechanism (e.g., reciprocating pump).
For known spring biased electromagnetic solenoids, a magnetic force is generated in the solenoid when the electrical current passes through the coil, thus causing the armature to move between the two end-stops. When a solenoid assembly, for example, a solenoid fuel injector, is required to operate at a high frequency, the magnetic force must be generated and decayed quickly. However, when the armature approaches a pole (or end-stop) of the solenoid, the magnetic force changes to a substantially higher value, and this high magnetic force is difficult to manage in such high frequency solenoid applications due to the time period required for the magnetic force to decay. Similarly stated, some known solenoids produce a magnetic force acting on the armature that changes, sometimes considerably, as a function of the distance between the armature and the pole (or end-stop).
Accordingly, some known systems are configured to implement a peak and hold driver to reduce the magnetic field by reducing the electrical current that passes through the solenoid when the armature approaches the pole (or end-stop). Such known systems, however, are expensive, cumbersome and require additional hardware.
Thus, a need exists for an improved and easy-to-implement solenoid design which provides a controlled magnetic force during operation of the solenoid.